Controlled release of diclofenac sodium through acrylamide grafted hydroxyethyl cellulose and sodium alginate

• The hydroxyethyl cellulose was successfully modified by grafting with acrylamide.
• The AAm-g-HEC was then blended with NaAlg and crosslinked with GA to form MPs.
• The % water uptake was found to be dependent on the amount of GA and AAm-g-HEC.
• Release data fitted to an empirical equation to investigate the diffusional exponent n.
• Values of n indicated that release mechanism shifted from anomalous to super Case-II.

To reinforce the hydroxyethyl cellulose for using it in biomedical and pharmaceutical applications as a drug delivery systems, the grafting of acrylamide onto hydroxyethyl cellulose (AAm-g-HEC) was achieved by Ce(IV) induced free radical polymerization. The AAm-g-HEC was then blended with sodium alginate (NaAlg) to prepare pH-sensitive interpenetrating network (IPN) microspheres (MPs) by emulsion-crosslinking method using glutaraldehyde (GA) as a crosslinking agent. The produced MPs are almost spherical in nature with smooth surfaces. Diclofenac sodium (DS), an anti-inflammatory drug, was successfully encapsulated into the MPs. The % encapsulation efficiency was found to vary between 54 and 67. The MPs were characterized by DSC, SEM and FTIR spectroscopy. In vitro release studies were carried out in simulated gastric fluid of pH 1.2 for 2 h followed by simulated intestinal fluid of pH 7.4 at 37 °C. The release data have been fitted to an empirical equation to investigate the diffusional exponent (n), which indicated that the release mechanism shifted from anomalous to the super Case-II transport.